Some Common Birds in Their Relation to AgricultureBeal, F. E. L. (Foster Ellenborough Lascelles)
Science
Some Common Birds in Their Relation to Agriculture
Beal, F. E. L. (Foster Ellenborough Lascelles)
Birds -- United States
The common and familiar bluebird (fig. 22) is an inhabitant of all the
States east of the Rocky Mountains from the Gulf of Mexico northward into
Canada. It winters as far north as southern Illinois, in the Mississippi
Valley, and Pennsylvania in the east; in spring it is one of the first
migrants to arrive in the Northern States, and is always welcomed as an
indication of the final breaking up of winter. It frequents orchards and
gardens, where it builds its nest in hollow trees, or takes advantage of a
nesting box provided by the enterprising farmer's boy.
[Illustration: Fig. 22.--Bluebird.]
So far as known, this bird has not been accused of stealing fruit or of
preying upon any crops. An examination of 205 stomachs showed that 76 per
cent of the food consists of insects and their allies, while the other
24 per cent is made up of various vegetable substances, found mostly in
stomachs taken in winter. Beetles constitute 28 per cent of the whole
food, grasshoppers 22, caterpillars 11, and various insects, including
quite a number of spiders, comprise the remainder of the insect diet. All
these are more or less harmful, except a few predaceous beetles, which
amount to 8 per cent, but in view of the large consumption of grasshoppers
and caterpillars, we can at least condone this offense, if such it may be
called. The destruction of grasshoppers is very noticeable in the months
of August and September, when these insects form more than 60 per cent of
the diet.
It is evident that in the selection of its food the bluebird is governed
more by abundance than by choice. Predaceous beetles are eaten in spring,
as they are among the first insects to appear; but in early summer
caterpillars form an important part of the diet, and are replaced a
little later by grasshoppers. Beetles are eaten at all times, except when
grasshoppers are more easily obtained.
So far as its vegetable food is concerned, the bluebird is positively
harmless. The only trace of any useful product in the stomachs consisted
of a few blackberry seeds, and even these more probably belonged to wild
than cultivated varieties. Following is a list of the various seeds
which were found: Blackberry, chokeberry, juniperberry, pokeberry,
partridgeberry, greenbriar, Virginia creeper, bittersweet, holly,
strawberry bush, false spikenard, wild sarsaparilla, sumac (several
species), rose haws, sorrel, ragweed, grass, and asparagus. This list
shows how little the bluebird depends upon the farm or garden to supply
its needs, and indicates that by encouraging the growth of some of these
plants, many of which are highly ornamental, the bird can be induced to
make its home on the premises.
Bluebirds are so well known that it seems unnecessary to urge anything
more in their favor; but in view of the fact that large numbers were
destroyed during the severe storm of 1895, more than ordinary vigilance
should be exercised in protecting them until they have regained their
normal abundance.
Public-domain text, read in full here on John Shaqi.
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